[time-nuts] HP Z3817A Reverse Engineering
Ed Palmer
ed_palmer at sasktel.net
Sun Jan 8 17:57:23 UTC 2012
Hi Azelio,
Thanks, but I already found that. I've moved quite a bit beyond that.
That message was one of the few in the archives that had any
significant info on this unit. For some reason, I find that surprising.
Ed
On 1/8/2012 11:33 AM, Azelio Boriani wrote:
> Have you already this?
>
>
>
> On the TIB (P1) DB-25 connector, I'm fairly confident about these:
>
> V+ pins 1 and 21
> V- pins 8 and 25
> 10MHz #1 pins 2/15 xfmr coupled, ~4.6V into 1M
> 10MHz #2 pins 23/16 xfmr coupled, ~4.6V into 1M
> 1PPS pin 14
>
> Supply voltage is dictated by Lucent DC-DC converter. Input is 18-36V,
> 1.9A.
>
> Still chasing down the other pins. Currently I am working on a possible
> disciplining input:
>
> input of some kind to U6/3 via 100 ohms pin 18, prob. diff with 4
> input of some kind to U6/2 via 100 ohms pin 4, prob. diff with 18
>
> The MMI (J1) DB-9 connector is RS-232, 9600baud, 8n1 and runs a a
> familiar SCPI interface.
>
>
>
>
>
> On Sun, Jan 8, 2012 at 6:20 PM, Ed Palmer<ed_palmer at sasktel.net> wrote:
>
>> I recently purchased a Motorola STLN4096A with the HP E1938A oscillator.
>> I bought it for the oscillator only.
>>
>> Then I got intrigued by the HP Z3817A GPSDO that's included. I've reverse
>> engineered most of it and I've got it running. The 1 PPS is really good (
>> 1000 measurements, Std. Dev. of<200 ps, min to max range of<1.5 ns) and
>> the HUP is very slowly dropping (currently at 13 us after ~1.5 days) as the
>> oscillator works out the kinks after it's long sleep. It's dropping much
>> slower than my Z3801A did when I first turned it on.
>>
>> There's one input that I haven't been able to figure out. I've got data
>> in and 1 PPS in from the GPS receiver. Everything seems to be working so
>> I'm at a loss what that the other input could be for. There are no clues
>> to it's function because it appears to go into one of the Xilinx chips.
>>
>> Does anyone have any more info on the unit? Has anyone figured out the
>> other input?
>>
>> I have searched the net and the archives. There's very little info or
>> discussion on this unit.
>>
>> Ed
>>
>>
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